1. Field of the Invention
This invention pertains in general to storing information in a web browser's cookie during a web-browsing session.
2. Description of the Related Art
Online advertising has grown significantly in recent years. Web pages often include space for informational content desired by the web page's visitors (referred to as users, who use the information presented on the web page), as well as space for advertising (ad) content. The advertising space on a web page is generally referred to as ad inventory. The publisher of the web page then offers its ad inventory for sale, directly or indirectly, to advertisers. Advertisers, again directly or indirectly, purchase advertising space to place individual instances of ad content, generally referred to as impressions. Impressions are presented to the user with the hope of inducing the user to perform some desired act including, for example, clicking on an impression, visiting a specific web page, signing up for online services or news from a particular web page, or purchasing merchandise from yet another web page. When the user performs the desired act, the user is deemed to have “converted.”
The online advertising industry includes many different types of advertisers that represent companies producing a wide variety of goods and services. The internet has grown rapidly in recent years, and concordantly the supply for ad inventory has also dramatically increased. However, given the wide variety of goods and services to be advertised, not all web pages have ad inventory that is valuable to a given advertiser. Thus, advertisers, often in partnership with third parties such as ad servers, try to identify ad inventory that is valuable to their customers. Ad servers help advertisers target particular web pages and audiences of users, instead of indiscriminately placing ads in front of a large number of users. To do this, ad servers collect statistics regarding user traffic on web pages to make better advertising inventory purchase decisions. These statistics include web pages visited by users and the actions taken by those users on the visited web pages. The goal of such targeted advertising is to increase the likelihood that the users the advertiser advertises to actually convert.
To collect statistics about a user a pixel tag may be embedded in a web page that the user requests. Typically, to embed a pixel tag, a code snippet is placed in the web page that is delivered to the user's web browser. The code snippet may, for example be written in HTML, XML, JavaScript, or any other programming language. When the browser processes the web page, the code snippet is executed (referred to herein as “firing the pixel tag”) causing the browser to transmit a message to a server identified in the code snippet. The message may include information regarding the internet protocol (IP) address of the computing device that executes the browser's rendition of the web page, the browser type, a timestamp, and the user's identity among other details. Upon receiving the message, the server can store this information and associate the user's identity with the stored information. However, the server would need a mechanism by which to determine if other information for the same user has already been stored with the server due to the user visiting other web pages that include pixel tags.
Employing web browser cookies is one way that a server can identify a particular user and thereby track the user's browsing activities. A web browser cookie is a few bits of data that an external server, such as a web page hosting server or a third party ad server, often transmits to the user's web browser, in response to a web page request initiated by the user. The web browser then stores this data on the user's computer, and associates the cookie with the external server.
A cookie comprises at least two parameters, namely the name of the cookie and its value. A subsequent request by the user to the same external server will then include this cookie (e.g., its name and value) with the request and transmit it back to the external server. In addition any other cookies (e.g., their names and values) stored on the user's computer that are associated with the same external server are also transmitted back to the external server with the subsequent request. If the user explicitly sends a request to the external server (e.g., the top level “page” requested by the user's browser includes the hostname of the external server), then the external server is referred to as the “first party” of this request and its cookie is a first party cookie.
Restated, if the external server is the same as the entity providing the requested web page, that entity (e.g., the web page hosting server) is the first party of the cookie. In comparison, if in the course of loading a top level web page a Pixel or Image or other piece of supplemental content is requested from a different external server, that entity (e.g., the third party ad server) is referred to as the “third party” and its cookie is a third party cookie. Stated differently, a third party is any server with a web domain different from the first party's web domain.
In all modern web browsers, servers are only allowed to read and write cookies related to their own domain. Some new versions of web browsers, notably Firefox™ and Safari™, are planning to or have already implemented a change which means that third parties can read, but cannot write or update, their own domain cookies when they are serving content in a third party context. This prevents a third party from using first party cookies to identify a user's browsing behavior.